Valve system for pneumatic cylinders

ABSTRACT

A valve system, for use with a cylinder having an extensible rod, includes a first valve assembly having a first inlet/outlet port, a check valve biased toward a closed state, the check valve having a check valve body at least partially receivable within a first port of the cylinder, a flow control valve positioned in series between the first inlet/outlet port and the check valve, and a first pilot port selectively communicable with a source of pressurized gas for opening the check valve. The valve system further includes a second valve assembly having a second inlet/outlet port, a second pilot port through which the pressurized gas must flow before being introduced to the first pilot port, and a valve body at least partially receivable within a second port of the cylinder.

FIELD OF THE INVENTION

The present invention relates to a valve system, and more particularlyto a valve system for use with a pneumatic cylinder.

BACKGROUND OF THE INVENTION

Pneumatic cylinders utilize a compressed gas to produce a force andaxially translate an extensible rod and piston. A single acting cylinderincludes a piston which is biased in a single direction by a spring oralternative biasing member. When the pressurized gas exerts a forceagainst the biasing member great enough to overcome a spring force, thebiasing member compresses, thereby allowing the piston and extensiblerod to translate. When the gas pressure decreases, the piston andextensible rod translate in the opposing direction. A double actingcylinder does not include a spring or biasing member, but instead reliesupon gas pressure to move the piston and extensible rod in opposingdirections, thereby requiring an influx of gas into the pneumaticcylinder to both extend and retract the piston and extensible rod.

SUMMARY OF THE INVENTION

The invention provides, in one aspect, a valve system for use with acylinder having an extensible rod. The valve system includes a firstvalve assembly having a first inlet/outlet port, a check valve biasedtoward a closed state, the check valve having a check valve body atleast partially receivable within a first port of the cylinder, a flowcontrol valve positioned in series between the first inlet/outlet portand the check valve, and a first pilot port selectively communicablewith a source of pressurized gas for opening the check valve. The valvesystem further includes a second valve assembly having a secondinlet/outlet port, a second pilot port through which the pressurized gasmust flow before being introduced to the first pilot port, and a valvebody at least partially receivable within a second port of the cylinder.

The invention provides, in another aspect, a method of controllingactuation of an extensible rod of a cylinder. The method includesdirectly attaching a first valve assembly to a first port on thecylinder, directly attaching a second valve assembly to a second port onthe cylinder, fluidly communicating a first pilot port of the firstvalve assembly and a second pilot port of the second valve assembly witha hose, directing pressurized gas through a check valve in the firstvalve assembly and the first cylinder port to cause the rod to undergoone of an extension operation or a retraction operation, directingpressurized gas through the second valve assembly and the secondcylinder port to cause the rod to undergo the other of the extensionoperation or the retraction operation, and directing pressurized gasfrom the second valve assembly, through the hose, to the first valveassembly to release the check valve and permit pressurized gas to beexhausted from the first cylinder port and the first valve assembly.

Other features and aspects of the invention will become apparent byconsideration of the following detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a valve system in accordance with anembodiment of the invention for use with a cylinder.

FIG. 2 is a top view of the valve system and cylinder of FIG. 1 with aschematic representation of adjoining valve structure.

FIG. 3 is a cross-sectional view of the valve system and cylinder ofFIG. 1, along section 3-3 in FIG. 2, illustrating an extensible rod ofthe cylinder in a central position.

FIG. 4 is a cross-sectional view of a first valve assembly of the valvesystem of FIG. 1 along section 4-4 in FIG. 3.

FIG. 5 is a cross-sectional view of the first valve assembly of FIG. 1along section 5-5 in FIG. 2.

FIG. 6 is a cross-sectional view of a second valve assembly of the valvesystem of FIG. 1 along section 6-6 in FIG. 3.

FIG. 7 is a cross-sectional view of the second valve assembly of FIG. 1along section 7-7 in FIG. 2.

FIG. 8 is a cross-sectional view of the valve system and cylinder ofFIG. 1, illustrating the cylinder during an extension operation.

FIG. 8A is an enlarged view of the first valve assembly of the valvesystem and cylinder of FIG. 8.

FIG. 8B is an enlarged view of the second valve assembly of the valvesystem and cylinder of FIG. 8.

FIG. 9 is a cross-sectional view of the valve system and cylinder ofFIG. 1, illustrating the cylinder during a retraction operation.

FIG. 9A is an enlarged view of the first valve assembly of the valvesystem and cylinder of FIG. 9.

FIG. 9B is an enlarged view of the second valve assembly of the valvesystem and cylinder of FIG. 9.

FIG. 10 is a cross-sectional view of the valve system and cylinder ofFIG. 1, illustrating the cylinder pressure being vented by depressing amanual release button.

FIG. 10A is an enlarged view of the first valve assembly of the valvesystem and cylinder of FIG. 10.

FIG. 10B is an enlarged view of the second valve assembly of the valvesystem and cylinder of FIG. 10.

FIG. 11 is a perspective view of a valve system in accordance withanother embodiment of the invention for use with a cylinder.

FIG. 12 is a top view of the valve system and cylinder of FIG. 11 with aschematic representation of adjoining valve structure.

FIG. 13 is a cross-sectional view of the valve system and cylinder ofFIG. 11, along section 13-13 in FIG. 12, illustrating an extensible rodof the cylinder in a central position.

FIG. 14 is a cross-sectional view of the valve system and cylinder ofFIG. 11, along section 14-14 in FIG. 12.

FIG. 15 is a perspective view of a second valve assembly of the valvesystem of FIG. 11.

FIG. 16 is a cross-sectional view of the second valve assembly alongsection 16-16 in FIG. 15.

FIG. 17 is a cross-sectional view of the second valve assembly alongsection 17-17 in FIG. 15.

FIG. 18 is a cross-sectional view of the valve system and cylinder ofFIG. 11, illustrating the cylinder during an extension operation.

FIG. 18A is an enlarged view of the first valve assembly of the valvesystem and cylinder of FIG. 18.

FIG. 18B is an enlarged view of the second valve assembly of the valvesystem and cylinder of FIG. 18.

FIG. 19 is a cross-sectional view of the valve system and cylinder ofFIG. 11, illustrating the cylinder during a retraction operation.

FIG. 19A is an enlarged view of the first valve assembly of the valvesystem and cylinder of FIG. 19.

FIG. 19B is an enlarged view of the second valve assembly of the valvesystem and cylinder of FIG. 19.

FIG. 20 is a cross-sectional view of the valve system and cylinder ofFIG. 11, illustrating the cylinder pressure being vented by depressing amanual release button.

FIG. 20A is an enlarged view of the first valve assembly of the valvesystem and cylinder of FIG. 20.

FIG. 20B is an enlarged view of the second valve assembly of the valvesystem and cylinder of FIG. 20.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting.

DETAILED DESCRIPTION

With reference to FIGS. 1-3, a valve system 10 for use with a pneumaticcylinder 12 is shown. The cylinder 12 includes a housing 14, dualinlet/outlet ports 16, 18 in fluid communication with a chamber 20defined within the housing 14, and an extensible rod 22 (FIG. 3). Theextensible rod 22 includes a piston 24 that separates the chamber 20into a first chamber portion 26 and a second chamber portion 28, thevolume of each of which is variable and dependent upon the position ofthe piston 24 within the chamber 20. As described in further detailbelow, the valve system 10 is operable to direct pressurized gas (e.g.,air) into the first chamber portion 26 or the second chamber portion 28,respectively, to cause the rod 22 to extend or retract.

With reference to FIG. 2, the valve system 10 is in fluid communicationwith a supply 30 or source of pressurized gas and an exhaust 32 (e.g., avent to atmosphere or a gas recycling system) via pneumatic lines 34, 36and a three-position valve 38. As described in further detail below, ina first position of the three-position valve 38 (shown in FIG. 2), bothof the first and second chamber portions 26, 28 of the cylinder 12 arevented, through the valve system 10, to the exhaust 32. In a secondposition (FIG. 8), the three-position valve 38 and the valve system 10direct pressurized gas from the pressurized gas source 30 to the firstchamber portion 26, while the second chamber portion 28 is vented to theexhaust 32, causing the rod 22 to extend. In a third position (FIG. 9),the three-position valve 38 and the valve system 10 direct pressurizedgas from the pressurized gas source 30 to the second chamber portion 28,while the first chamber portion 26 is vented to the exhaust 32, causingthe rod 22 to retract.

With reference to FIGS. 1 and 3, the valve system 10 includes a firstvalve assembly 42 fluidly connected with the rear inlet/outlet port 16of the cylinder 12 or first cylinder port 16, which is in fluidcommunication with the first chamber portion 26. The first valveassembly 42 includes a check valve 44 (FIG. 5) having a check valve body46 directly attached and at least partially receivable within the rearinlet/outlet port 16 of the cylinder 12 (FIG. 3). Specifically, thecheck valve body 46 includes a threaded end 48 (FIG. 5) having auniversal thread form compatible with multiple different threadconfigurations (e.g., unified, metric, square, etc.). In this manner,the first valve assembly 42 is compatible with pneumatic cylinders 12having inlet/outlet ports with NPT, NPTF, BSPP, BSPT, JIS (PF) and JIS(PT) thread forms. The check valve body 46 also includes a seal 50positioned adjacent the threaded end 48 that is engageable with theopening of the inlet/outlet port 16 to prevent leakage from theinlet/outlet port 16. The seal 50 may be made from a polymer or anothermaterial.

With continued reference to FIG. 5, the check valve 44 also includes aninternal seat 52 defining a circular orifice 54 coaxial with alongitudinal axis 56 of the check valve body 46, a seal member 58 (e.g.,a check ball), and a biasing member 60 (e.g., a compression spring) forbiasing the ball 58 against the seat 52 to thereby close the orifice 54.Accordingly, when the check ball 58 is in a closed position, the orifice54 is closed and the interior of the check valve body 46 is separatedinto an upper cavity 62 above the valve seat 52 (from the frame ofreference of FIG. 5) and a lower cavity 64 beneath the valve seat 52.The check valve body 46 includes multiple apertures 66, each of which isoriented transverse to the longitudinal axis 56, exposed to the uppercavity 62, while the lower cavity 64 is directly exposed to and in fluidcommunication with the first chamber portion 26 of the cylinder 12 whenthe first valve assembly 42 is attached to the rear inlet/outlet port 16of the cylinder 12.

With continued reference to FIG. 5, the check valve 44 further includesa sleeve 72 positioned within the check valve body 46, a plunger 74 thatis slidable within the sleeve 72 along the longitudinal axis 56, and abiasing member 76 (e.g., a compression spring) for biasing the plunger74 upwards (from the frame of reference of FIG. 5) and away from thecheck ball 58. The sleeve 72 defines an internal chamber 78 that issealed from the upper cavity 62 by an O-ring 80 on an exterior of thesleeve and a lip seal 84, through which a tip 86 of the plunger 74extends, within a stepped aperture 88 in a bottom end 90 of the sleeve72. The plunger 74 also includes a circular lip seal 92 on its exteriorthat is in sliding contact with an interior wall of the sleeve 72,thereby separating the sleeve chamber 78 into an upper sleeve chamber 94(from the frame of reference of FIG. 5) and a lower sleeve chamber 96 inwhich the spring 76 is located. The volume of each of the upper andlower sleeve chambers 94, 96 is variable depending upon the position ofthe plunger 74 relative to the sleeve 72.

The sleeve 72 includes an upper circumferential recess 110 on itsexterior and multiple apertures 112, each of which is orientedtransverse to the longitudinal axis 56, fluidly interconnecting theupper sleeve chamber 94 and the upper circumferential recess 110. Thecheck valve body 46 includes a single aperture 114, which is alsooriented transverse to the longitudinal axis 56, having a radially innerend directly exposed to and in fluid communication with the uppercircumferential recess 110 in the sleeve 72 and a radially outer endexposed to an exterior surface of the check valve body 46. The sleeve 72also includes a lower circumferential recess 116 on its exterior andmultiple apertures 118, each of which is oriented transverse to thelongitudinal axis 56, fluidly interconnecting the lower sleeve chamber96 and the lower circumferential recess 116. The check valve body 46includes a single aperture 120, which is also oriented transverse to thelongitudinal axis 56, having a radially inner end directly exposed toand in fluid communication with the lower circumferential recess 116 inthe sleeve 72 and a radially outer end exposed to the exterior surfaceof the check valve body 46.

With continued reference to FIG. 5, the check valve 44 also includes anend cap 122, positioned above the sleeve 72, having a cylindrical bore124 coaxial with the longitudinal axis 56 and a manual release button126 slidably positioned within the cylindrical bore 124. A top end 128of the button 126 is exposed and accessible by an operator outside thecheck valve body 46, while a bottom end 130 of the button 126 is abuttedwith the plunger 74. The button 126 includes an O-ring 148 on itsexterior to prevent any pressurized gas within the upper sleeve chamber94 from escaping through the cylindrical bore 124 in the end cap 122.

With reference to FIGS. 4 and 5, the first valve assembly 42 alsoincludes a first flow control valve 136 coupled to the check valve body46. The first flow control valve 136 includes an insert 138, a valvemember or needle 140, and a one-way seal 142. The first flow controlvalve 136 is received within a banjo fitting 144, a hoop portion 146 ofwhich is slip-fit over the check valve body 46 and overlapping theapertures 66 in the check valve body 46 exposed to the upper cavity 62.The hoop portion 146 is stepped to seal against an O-ring 82 locatedabove the apertures 66, and another O-ring 150 located within a recess152 in the check valve body 46 below the apertures 66 (from the frame ofreference of FIG. 5). The O-rings 82, 150 provide a seal between thebanjo fitting 144 and the check valve body 46 to prevent unwantedleakage of the pressurized gas. The banjo fitting 144 further includes acylindrical portion 154 that extends transverse to the longitudinal axis56 and is hollow, defining a fitting chamber 156, to support the insert138, needle 140, and one-way seal 142.

The insert 138 is tubular, including a stepped inside diameter, and isaxially aligned with the cylindrical portion 154 of the banjo fitting144. The insert 138 includes radially extending apertures 158 thatprovide a fluid flow path between the fitting chamber 156 and theinterior of the insert 138. The insert 138 further includes respectiveopenings 160 at opposite ends 162, 164, with a first end 162 of theinsert 138 being exposed to the upper cavity 62 of the check valve body46, and a second end 164 to which an end cap 98 is affixed through whichthe needle 140 extends. The needle 140 includes a threaded portion 166engaged with corresponding threads on the end cap 98, and a lock nut 168is threaded onto the threaded portion 166 of the needle 140 for abuttingthe end cap 98 and rotationally constraining the needle 140 relative tothe end cap 98 once the position of the needle 140 within the insert 138is set. The needle 140 also includes a knob 170 at the distal endthereof that is graspable by an operator for setting the position of theneedle 140 within the insert 138.

With continued reference to FIGS. 4 and 5, the needle 140 includes astep 172 that rests against a seat 174 of the insert 138 when the needle140 is in a fully closed position. Fluid flow between the needle 140 andinsert 138 is prohibited when the needle 140 is in the fully closedposition. The needle 140 is unseated from the seat 174 into an openposition (i.e., any position except the fully closed position) byrotating the knob 170 in an opening direction, which rotates thethreaded portion 166 of the needle 140 relative to the end cap 98 totranslate the needle 140. Fluid flow between the needle 140 and insert138 is allowed when the needle 140 is in the open position and isvariable based on the displacement of the step 172 relative to the seat174. As the distance between the step 172 and the seat 174 increases,the rate at which gas can flow between the needle 140 and the insert 138also increases. The needle 140 also includes an O-ring 176 locatedbetween the step 172 and the threaded portion 166 that prohibits gaswithin the insert 138 from leaking past the end cap 98.

The one-way seal 142 surrounds the insert 138 and abuts both the insert138 and the cylindrical portion 154 of the banjo fitting 144. Theone-way seal 142 is made of a resilient material, permitting the seal toselectively deflect or deform in response to the application of a gaspressure on one side of the seal 142 to provide a flow path from thefitting chamber 156 to the check valve 44, thereby bypassing the needle140. Specifically, the one-way seal 142 includes an annular rim 178 thatis obliquely oriented relative to a longitudinal axis 180 of the needle140, such that pressurized gas acting on a first side 182 of the seal142 is capable of deflecting the rim 178 to provide a flow path betweenthe seal 142 and the cylindrical portion 154 of the banjo fitting 144,and preventing such a path in the opposing direction. In the opposingdirection, pressurized gas presses a second side 184 of the seal 142(i.e., opposite the first side 182 of the seal 142) into contact withthe cylindrical portion 154, preventing the flow of pressurized gastherebetween. In this manner, the flow control valve 136 selectivelyprovides a flow path between the check valve 44 and a first inlet/outletport 186.

As shown in FIG. 4, first valve assembly 42 further includes a firstinlet/outlet port 186 coupled to the banjo fitting 144 and incommunication with the fitting chamber 156. In the illustratedembodiment, the first inlet/outlet port 186 and the banjo fitting 144are connected by a swivel joint 188, which permits the firstinlet/outlet port 186 to be reoriented relative to the banjo fitting144. An O-ring 190 is located adjacent the swivel joint 188 to seal thebanjo fitting 144 to the first inlet/outlet port 186.

The first inlet/outlet port 186 communicates with the three positionvalve 38 via the hose 34 (see FIGS. 1 and 2). When connected to theexhaust 32, the first inlet/outlet port 186 functions as an outlet toallow pressurized gas to exhaust from the first chamber portion 26 ofthe cylinder 12, through the check valve 44, through the first flowcontrol valve 136, and through the first inlet/outlet port 186 beforebeing discharged to the exhaust 32. When connected to the air supply 30,the first inlet/outlet port 186 functions as an inlet to allowpressurized gas to flow into the first inlet/outlet port 186, throughthe first flow control valve 136, and through the check valve 44 beforeentering the first chamber portion 26 of the cylinder 12. With referenceto FIG. 4, the inlet/outlet port 186 includes a stepped region 192 sizedto receive a quick-lock fitting 194 (e.g., a push-lock fitting) forconnecting the hose 34 (i.e., from the three position valve 38) to theinlet/outlet port 186. Such a push-lock fitting 194 is commerciallyavailable from Camozzi Pneumatics, Inc. of McKinney, Tex., United Statesof America.

With reference to FIG. 5, the first valve assembly 42 also includes afirst pilot port 196 in communication with the check valve 44. In theillustrated embodiment, the first pilot port 196 is defined by acylindrical portion 198 of a banjo fitting 210 in which a fitting 212(e.g., a push-lock fitting) is received. The hoop portion 214 of thebanjo fitting 210 is slip-fit over the check valve body 46 and overlapsthe single aperture 114 in the check valve body 46 exposed to the uppersleeve chamber 94. As shown, the banjo fitting 210 defining the firstpilot port 196 is stackable upon the banjo fitting 144 in which thefirst flow control valve 136 is received. The hoop portion 214 sealsagainst the check valve body 46 via two O-rings 216, 218, one locatedabove the single aperture 114, the other located below the singleaperture 114 (from the frame of reference of FIG. 5) and located withinrespective recesses 220, 222 in the check valve body 46. The O-rings216, 218 provide a seal between the banjo fitting 210 and the checkvalve body 46 to prevent unwanted leakage of the pressurized gas. Thecylindrical portion 198 of the banjo fitting 210 extends transverse tothe longitudinal axis 56 and is hollow, defining the first pilot port196, to support the fitting 212. The first pilot port 196 is incommunication with the single aperture 114, and therefore the uppersleeve chamber 94, via a cavity 208 that interconnects the hoop andcylindrical portions 214, 198 of the banjo fitting 210. The fitting issized to accept a hose or pneumatic line 206 (FIGS. 1-3), the purpose ofwhich is described in further detail below.

With reference to FIGS. 1-3 and 6-7, the valve system 10 includes asecond valve assembly 224 fluidly connected with the front inlet/outletport 18 of the cylinder 12 or second cylinder port 18, which is in fluidcommunication with the second chamber portion 28. The second valveassembly 224 includes a valve body 226 (FIG. 7) directly attached and atleast partially receivable within the front inlet/outlet port 18 of thecylinder 12 (FIG. 3). Specifically, the valve body 226 includes athreaded end 228 (FIG. 7) having a thread form compatible with multipledifferent thread configurations, identical to the threaded end 48 of thecheck valve body 46. The valve body 226 also includes a seal 200positioned adjacent the threaded end 228 that is engageable with theopening of the inlet/outlet port 18 to prevent leakage from theinlet/outlet port 18. Similar to the seal 50, the seal 200 may be madefrom a polymer or another material.

With continued reference to FIG. 7, the interior of the valve body 226includes a single chamber 230 in continuous fluid communication with thesecond chamber portion 28 of the cylinder 12, a second flow controlvalve 232, and a second pilot port 234. Unlike the first valve assembly42, the valve body 226 does not include a check valve, and thereforepermits free flow of pressurized gas at all times throughout the singlechamber 230 of the valve body 226. The single chamber 230 includes afirst cavity 236 having a lower end in fluid communication with thefront inlet/outlet port 18 and an upper end in fluid communication withradially extending apertures 238 exposed to the outer periphery of thevalve body 226. The single chamber 230 also includes a coaxial secondcavity 240 having a smaller diameter than the first cavity 236, and athird cavity 242 that extends transverse to a longitudinal axis 202 ofthe valve body 226 and that is exposed to an outer periphery of thevalve body 226.

With reference to FIGS. 6 and 7, the second valve assembly 224 alsoincludes a second flow control valve 232 coupled to the valve body 226.Though annotated with new reference numerals, except as otherwisedescribed, the second flow control valve 232 is identical to the firstflow control valve 136. The second flow control valve 232 includes aninsert 244, a valve member or needle 246, and a one-way seal 248. Thesecond flow control valve 232 is received within a cylindrical portion250 of a banjo fitting 252, a hoop portion 254 of which is slip-fit overthe valve body 226 and overlapping the apertures 238 in the valve body226 exposed to the first cavity 236. The hoop portion 254 is stepped toseal against an O-ring 256 located above the apertures 238, and anotherO-ring 258 located within a recess 260 in the valve body 226 below theapertures 238 (from the frame of reference of FIG. 7). The O-rings 256,258 provide a seal between the banjo fitting 252 and the valve body 226to prevent unwanted leakage of the pressurized gas. The banjo fitting252 further includes a cylindrical portion 250 that extends transverseto the longitudinal axis 202 and is hollow, defining a fitting chamber262, to support the insert 244, needle 246, and one-way seal 248.

As shown in FIG. 6, the second valve assembly 224 further includes asecond inlet/outlet port 266 coupled to the banjo fitting 252 and incommunication with the fitting chamber 262. In the illustratedembodiment, the second inlet/outlet port 266 and the banjo fitting 252are connected by a swivel joint 268, which permits the secondinlet/outlet port 266 to be reoriented relative to the banjo fitting252. An O-ring 270 is located adjacent the swivel joint 268 to seal thebanjo fitting 252 to the second inlet/outlet port 266.

The second inlet/outlet port 266 communicates with the three positionvalve 38 via the hose 36 (FIGS. 1 and 2). When connected to the exhaust32, the second inlet/outlet port 266 functions as an outlet to allowpressurized gas to exhaust from the second chamber portion 28 of thecylinder 12, through the single chamber 230 of the valve body 226,through the second flow control valve 232, and through the secondinlet/outlet port 266 before being discharged to the exhaust 32. Whenconnected to the air supply 30, the second inlet/outlet port 266functions as an inlet to allow pressurized gas to flow through thesecond inlet/outlet port 266, through the second flow control valve 232,and through the single chamber 230 of the valve body 226 before reachingthe second chamber portion 28 of the cylinder 12. With reference to FIG.6, the inlet/outlet port 266 includes a stepped region 272 sized toreceive a quick-lock fitting 274 (e.g., a push-lock fitting) forconnecting the hose 36 (i.e., from the three position valve 38) to theinlet/outlet port 266. Such a push-lock fitting 274 is commerciallyavailable from Camozzi Pneumatics, Inc. of McKinney, Tex., United Statesof America.

With reference to FIG. 7, the second valve assembly 224 also includes asecond pilot port 234 in communication with the single chamber 230. Inthe illustrated embodiment, the second pilot port 234 is defined by acylindrical portion 278 of a banjo fitting 280 in which a fitting 282(e.g., a push-lock fitting) is received. The hoop portion 284 of thebanjo fitting 280 is slip-fit over the valve body 226 and overlaps theoutlets 286 of the third cavity 242. As shown, the banjo fitting 280defining the second pilot port 234 is stackable upon the banjo fitting252 in which the second flow control valve 232 is received. The hoopportion 284 seals against the valve body 226 via two O-rings 288, 290,one located above the outlets 286, the other located below the outlets286 (from the frame of reference of FIG. 7) and located withinrespective recesses 292, 294 in the valve body 226. The O-rings 288, 290provide a seal between the banjo fitting 280 and the valve body 226 toprevent unwanted leakage of the pressurized gas. The hoop portion 284 issized to provide an annular gap 296 outside the valve body 226 andbetween the O-rings 288, 290 to connect the outlets 286 of the thirdcavity 242. The cylindrical portion 278 of the banjo fitting 280 extendstransverse to the longitudinal axis 202 and is hollow, defining thesecond inlet/outlet port 266, to support the fitting 282. The secondinlet/outlet port 282 is in communication with the third cavity 242 viaa channel 298 that interconnects the hoop and cylindrical portions 284,278 of the banjo fitting. The fitting 282 is sized to accept the hose orpneumatic line 206 (FIGS. 1-3) described above with respect to the firstpilot port 196.

The valve system 10 is operable in three modes depending upon theposition of the three position valve 38: a first mode, a second mode,and a third mode. As shown in FIGS. 8, 8A, and 8B, an extensionoperation is performed in a first mode. In the first mode, the threeposition valve 38 is shifted to the second position and connects thepressurized gas source 30 to the first valve assembly 42, and the secondvalve assembly 224 to the exhaust 32. The first inlet/outlet port 186functions as an inlet to direct the pressurized gas toward the firstflow control valve 136. Upon entering the first banjo fitting 144 at thefitting chamber 156, the pressurized gas acts on the first side 182 ofthe one-way seal 142 to inwardly deflect the rim 178 of the one-way seal142 (FIG. 8A), permitting the pressurized gas to bypass the flow controlvalve 136 on route to the check valve 44 (arrow A1).

Once past the flow control valve 136, the pressurized gas enters theupper cavity 62 of the check valve body 46 via the apertures 66. Uponthe upper cavity 62 reaching a high enough pressure to overcome thespring force of the biasing member 60 and unseat the seal member 58 fromthe valve seat 52, the pressurized gas flows around the seal member 58and flows through the lower cavity 64 in the check valve body 46 onroute to the first cylinder chamber or first chamber portion 26. Theincrease in pressure in the first cylinder chamber 26 applies a force tothe piston 24, thereby extending the rod 22. The rod 22 extends at aspeed that is dependent upon the degree to which the second flow controlvalve 232 is opened (and the exhaust flow rate of the pressurized gasfrom the second cylinder chamber or second chamber portion 28 as meteredby the second flow control valve 232) until the piston 24 bottoms out orstops in response to the application of a reaction force on the rod 22equal and opposite the force applied to the piston 24 by the pressurizedgas in the first cylinder chamber 26.

Simultaneously with pressurized gas entering the first cylinder chamber26 via the first valve assembly 42 (arrow A1 in FIG. 8A), thepressurized gas within the second cylinder chamber 28 is exhaustedthrough the second flow control valve 232 and the second inlet/outletport 266 (i.e., functioning as an outlet port) on route to the exhaust32 (arrow A2 in FIG. 8B). Because the second valve assembly 224 does notinclude a check valve, the pressurized gas in the second cylinderchamber 28 is exhausted through the flow control valve 232 at avolumetric or mass flow rate that is dependent upon the degree to whichthe flow control valve 232 is opened. In other words, the greater thespacing between the step 300 on the needle 246 and the seat 302 definedon the insert 244, the higher the flow rate that gas can be exhaustedfrom the second chamber portion 28, and the smaller the spacing betweenthe step 300 on the needle 246 and the seat 302 defined on the insert244, the lower the flow rate that gas can be exhausted from the secondchamber portion 28. Accordingly, during the extension operation shown inFIGS. 8, 8A, and 8B, the second flow control valve 232 meters the returnof pressurized gas from the second cylinder chamber 28 to the exhaust32. In practical applications, the degree to which the flow controlvalve 232 is opened is preset and remains unchanged during operation.

When the extensible rod 22 has translated the desired amount, orattained an equilibrium of forces acting on it, the three position valve38 is returned to the first position, coinciding with the second mode ofoperation. In the second mode, the three position valve 38 connects bothof the first and second inlet/outlet ports 186, 266 to the exhaust. Theseal member 58 is biased against the valve seat 52 to prevent the firstcylinder chamber 26 from being vented to the exhaust 32, maintaining thepressurized gas within the first cylinder chamber 26 and the resultantforce acting on the piston 24 of the extensible rod 22. However, thesecond cylinder chamber 28 remains vented to the exhaust 32. The valvesystem 10 and cylinder 12 may be operated in the second mode, forexample, when it is desired to maintain a clamping force on an object,with the rod 22 extended, but fluidly disconnect the first cylinderchamber 26 from the source 30 of pressurized gas.

As shown in FIGS. 9, 9A, and 9B, a retraction operation is performed inthe third mode. In the third mode, the three position valve 38 isshifted to the third position and connects the pressurized gas source 30to the second valve assembly 224 and connects the first valve assembly42 to the exhaust 32. Specifically, the second inlet/outlet port 266functions as an inlet to direct the pressurized gas toward the secondflow control valve 232. Upon entering the banjo fitting 252 at thefitting chamber 262, the pressurized gas acts on a first side 304 of theone-way seal 248 to inwardly deflect the rim 306 of the one-way seal 248(arrow A3 in FIG. 9B), permitting the pressurized gas to bypass thesecond flow control valve 232 and enter the first cavity 236 of thevalve body. Once in the first cavity 236, the pressurized gas branchesalong two paths (designated by arrows A4 and A5). On the first path(arrow A4), the pressurized gas builds pressure within the secondcylinder inlet/outlet port 18 and the second cylinder chamber 28. Theincrease in pressure in the second cylinder chamber 28 (i.e., applied bythe pressurized gas) applies a force to the piston 24, therebyretracting the rod 22. The rod 22 retracts at a speed that is dependentupon the degree to which the first flow control valve 136 is opened (andthe exhaust flow rate of the pressurized gas from the first cylinderchamber 26 as metered by the first flow control valve 136) until thepiston 24 bottoms out or stops in response to the application of areaction force on the rod 22 equal and opposite the force applied to thepiston by the pressurized gas in the second cylinder chamber 28.

Simultaneously, the pressurized gas continues along the second path(arrow A5), which extends from the first cavity 236 of the valve body tothe second pilot port 234 and the second fitting 282 (which supports asecond end of the hose 206) via the second and third cavities 240, 242.The pressurized gas enters the second end of the hose 206, traverses thehose 206, and exits the first end of the hose 206 to flood the uppercircumferential recess 110 and the upper sleeve chamber 94 of the firstvalve assembly 42 (at arrow A6). Pressure builds within the upper sleevechamber 94 against the top surface of the plunger 74 until the returnforce of the spring 76 biasing the plunger 74 is overcome, displacingthe plunger 74 along the longitudinal axis 56 until it contacts andunseats the seal member 58, overcoming the spring force of the biasingmember 60 and allowing pressurized gas in the first cylinder chamber 26to vent to the exhaust 32 through the first flow control valve 136 asthe second cylinder chamber 28 is simultaneously flooded withpressurized gas. A positive piston ratio (e.g., one that is greater than1:1) of the plunger 74 allows the pressurized gas within the uppersleeve chamber 94 to overcome the backpressure in the first cylinderchamber 26 acting on the ball 58. The piston ratio is the quotient ofthe area of the top surface of the plunger 74 divided by the areaoutlined by the orifice 44. The lower sleeve chamber 96 is vented to theatmosphere via the radially extending apertures 118 through the sleeve72, the lower circumferential recess 116 on the outer periphery of thesleeve 72, the aperture 120 in the banjo fitting 210 and check valvebody 46, and an axial gap 308 defined between the banjo fittings 144,210. Accordingly, additional gas pressure does not build in the lowersleeve chamber 96 as the plunger 74 is displaced downward within thesleeve 72. Accordingly, a pneumatic pilot circuit for actuating theplunger 74 and opening the check valve 44 is directed through the secondvalve assembly 224 on route to the first valve assembly 42.

Further, as shown in FIGS. 10, 10A, and 10B, the plunger 74 may bemanually actuated via operator input or contact with the button 126.When an operator depresses the button 126 (e.g., with a screwdriver,with a finger, etc.), the button 126 and plunger 74 move toward the sealmember 58 in unison to unseat the seal member 58 as described above,venting pressurized gas from the first cylinder chamber 26 through theflow control valve 136 along arrow A7, to the exhaust 32 when the valve38 is in the first position.

Regardless of the method (i.e., using a pneumatic force on the plunger74 or a physical input of force on the plunger 74 by depressing thebutton 126), once the seal member 58 is unseated, the pressurized gaswithin the first cylinder chamber 26 is exhausted through the first flowcontrol valve 136 and the first inlet/outlet port 186 (i.e., functioningas an outlet port) on route to the exhaust 32 (arrow A7). Thepressurized gas in the first cylinder chamber 26 is exhausted throughthe first flow control valve 136 at a volumetric or mass flow rate thatis dependent upon the degree to which the flow control valve 136 isopened. In other words, the greater the spacing between the step 172 onthe needle 140 and the seat 174 defined on the insert 138, the higherthe flow rate that gas can be exhausted from the first chamber portion26, and the smaller the spacing between the step 172 on the needle 140and the seat 174 defined on the insert 138, the lower the flow rate thatgas can be exhausted from the first chamber portion 26. Accordingly,during the retraction operations shown in FIGS. 9, 9A, 9B, 10, 10A, and10B, the first flow control valve 136 meters the return of pressurizedgas from the first cylinder chamber 26 to the exhaust 32. In practicalapplications, the degree to which the flow control valve 136 is openedis preset and remains unchanged during operation.

When the extensible rod 22 has translated the desired amount, orattained an equilibrium of forces acting on it, the three position valve38 is returned to the first position. As the pressure within the secondvalve assembly 224 and the second chamber portion 28 is exhausted,pressure within the upper sleeve chamber 94 decreases, allowing theplunger 74 and the seal member 58 to return to their biased positions.Therefore, the exhaust passage of the first chamber portion 26 past theseal member 58 is blocked, and the second cylinder chamber 28 vents tothe exhaust 32 until the first and second chamber portions 26, 28achieve equilibrium.

The valve system 10 can be tightly packaged around the cylinder 12,requiring less space for installation of the cylinder 12 in its end-useapplication and reducing clutter of pneumatic hoses connected to thecylinder 12. Specifically, by directing the pneumatic pilot circuit foractuating the plunger 74 through the second valve assembly 224, lesshose is required for plumbing the valve assemblies 42, 224 to thecylinder 12, reducing the likelihood of a hose or fitting failure andthe cylinder 12 going off-line within its end-use application.

With respect to FIGS. 11-20B, another embodiment of a valve system isshown with like features being identified with like reference numeralsincremented by one-thousand. FIGS. 11-20B illustrate a valve system 1010for use with a pneumatic cylinder 1012. The cylinder 1012 includes dualinlet/outlet ports 1016, 1018 in fluid communication with a chamber 1020defined within the housing 1014, and an extensible rod 1022 (FIG. 13).The extensible rod 1022 includes a piston 1024 that separates thechamber 1020 into a first chamber portion 1026 and a second chamberportion 1028, the volume of each of which is variable and dependent uponthe position of the piston 1024 within the chamber 1020. As described infurther detail below, the valve system 1010 is operable to directpressurized gas (e.g., air) into the first chamber portion 1026 or thesecond chamber portion 1028, respectively, to cause the rod 1022 toextend or retract.

With reference to FIGS. 11-17, the valve system 1010 includes a secondvalve assembly 1224, fluidly connected with the front inlet/outlet port1018 of the cylinder 1012 or second cylinder port 1018, which is influid communication with the second chamber portion 1028. The secondvalve assembly 1224 includes a valve body 1226 (FIG. 15) directlyattached and at least partially receivable within the front inlet/outletport 1018 of the cylinder 1012 (FIG. 13). Specifically, the valve body1226 includes a threaded end 1228 (FIGS. 15 and 16) having a thread formcompatible with multiple different thread configurations. The valve body1226 also includes a seal 1200 positioned adjacent the threaded end 1228that is engageable with the opening of the inlet/outlet port 1018 toprevent leakage from the inlet/outlet port 1018. The seal 1200 may bemade from a polymer or another material.

With reference to FIGS. 16 and 17, the interior of the valve body 1226includes a chamber 1230 that provides fluid communication between thesecond chamber portion 1028 of the cylinder 1012, a second inlet/outletport 1266, and a second pilot port 1234, with the inlet/outlet port 1266and the pilot port 1234 being separated from the second chamber portion1028 by a second flow control valve 1232 located within the chamber1230. The second flow control valve 1232 includes an insert 1244, avalve member or needle 1246, and a one-way seal 1248.

The insert 1244 is tubular, including a stepped inside diameter, and isaxially aligned with a longitudinal axis 1180 of the chamber 1230. Theinsert 1244 includes radially extending apertures 1310 that provide afluid flow path between the inlet/outlet port 1266 and the interior ofthe insert 1244. The insert 1244 further includes respective openings atopposite ends 1312, 1314, with a first end 1312 of the insert 1244 beingexposed to the second chamber portion 1028, and a second end 1314 towhich an end cap 1316 is affixed and through which the needle 1246extends. The needle 1246 includes a threaded portion 1318 engaged withcorresponding threads on the end cap 1316, and a lock nut 1320 isthreaded onto the threaded portion 1318 of the needle 1246 for abuttingthe end cap 1316 and rotationally constraining the needle 1246 relativeto the end cap 1316 once the position of the needle 1246 within theinsert 1244 is set. The needle 1246 also includes a knob 1322 at thedistal end thereof that is graspable by an operator for setting theposition of the needle 1246 within the insert 1244. The needle 1246includes a step 1300 that rests against a seat 1302 of the insert 1244when the needle 1246 is in a fully closed position. Fluid flow betweenthe needle 1246 and insert 1244 is prohibited when the needle 1246 is inthe fully closed position. The needle 1246 is unseated from the seat1302 into an open position (i.e., any position except the fully closedposition) by rotating the knob 1322. Fluid flow between the needle 1246and insert 1244 is allowed when the needle 1246 is in the open positionand is variable based on the displacement of the step 1300 relative tothe seat 1302. As the distance between the step 1300 and the seat 1302increases, the rate at which gas can flow between the needle 1246 andthe insert 1244 also increases.

The one-way seal 1248 surrounds the insert 1244 and abuts both theinsert 1244 and the valve body 1226 (defining the chamber 1230). Theone-way seal 1248 is made of a resilient material, permitting the sealto selectively deflect or deform in response to the application of a gaspressure on one side of the seal 1248 to provide a flow path from thesecond inlet/outlet port 1266 to the front inlet/outlet port 1018,thereby bypassing the needle 1246. The one-way seal 1248 does not deformor deflect in response to the application of a gas pressure on the otherside of the seal 1248, thereby preventing a gas pressure from the frontinlet/outlet port 1018 from bypassing the needle 1246. In this manner,the flow control valve 1232 selectively provides a flow path between thesecond inlet/outlet port 1266 and the front inlet/outlet port 1018.

The chamber 1230 includes a first cavity 1236 having a lower end influid communication with the front inlet/outlet port 1018 and an upperend in communication with a second cavity 1240. The second cavity 1240is connected to the first cavity via the gap between the step 1300 andthe seat 1302 when the needle 1246 is in an open position, andselectively via the one-way seal 1248 (i.e., when the one-way seal 1248is deformed). The second cavity 1240 is delimited by the valve body1226, the insert 1244, and the one-way seal 1248 and is exposed directlyto the pilot port 1234 and inlet/outlet port 1266. As shown in FIG. 17,the second cavity 1240 has an annular cross-sectional shape and fluidlyconnects the pilot port 1234 and the inlet/outlet port 1266, such thatfluid flow between the inlet/outlet port 1266 and the pilot port 1234 ispermitted around the flow control valve 1232 regardless of the positionof the needle 1246.

As shown in FIGS. 15 and 17, the second inlet/outlet port 1266 is formedintegrally with the valve body 1226. The second inlet/outlet port 1266communicates with the three position valve 1038 via the hose 1036 (FIGS.11 and 12). When connected to the exhaust 1032, the second inlet/outletport 1266 functions as an outlet to allow pressurized gas to exhaustfrom the second chamber portion 1028 of the cylinder 1012, through thechamber 1230 of the valve body 1226, through the second flow controlvalve 1232, and through the second inlet/outlet port 1266 before beingdischarged to the exhaust 1032. When connected to the air supply 1030,the second inlet/outlet port 1266 functions as an inlet to allowpressurized gas to flow through the second inlet/outlet port 1266,through the second flow control valve 1232, and through the chamber 1230of the valve body 1226 before reaching the second chamber portion 1028of the cylinder 1012. With reference to FIG. 17, the inlet/outlet port1266 includes a stepped region 1272 sized to receive a quick-lockfitting 1274 (e.g., a push-lock fitting) for connecting the hose 1036(i.e., from the three position valve 1038) to the inlet/outlet port1266. Such a push-lock fitting 1274 is commercially available fromCamozzi Pneumatics, Inc. of McKinney, Tex., United States of America.

With continued reference to FIGS. 15 and 17, the second pilot port 1234is also formed integrally with the valve body 1226. The second pilotport 1234 includes a hollow cylindrical portion 1278 in which a fitting1282 (e.g., a push-lock fitting like fitting 1274) is received. Thefitting 1282 is sized to accept a hose or pneumatic line 1206 (FIGS.11-13), the hose 1206 additionally connected to a first pilot port 1196(FIG. 18A) of a first valve assembly 1042.

Like the valve system 10 described above, the valve system 1010 isoperable in three modes depending upon the position of the threeposition valve 1038: a first mode, a second mode, and a third mode. Asshown in FIGS. 18, 18A, and 18B, an extension operation is performed ina first mode. In the first mode, the three position valve 1038 isshifted to the second position and connects the pressurized gas source1030 to the first valve assembly 1042, and the second valve assembly1224 to the exhaust 1032. The first valve assembly 1042 functions in thesame manner as described above with respect to the first mode of valvesystem 10. Pressurized gas from the first valve assembly 1042 flows intothe first chamber portion 1026. The increase in pressure in the firstcylinder chamber 1026 applies a force to the piston 1024, therebyextending the rod 1022. The rod 1022 extends at a speed that isdependent upon the degree to which the second flow control valve 1232 isopened until the piston 1024 bottoms out or stops in response to theapplication of a reaction force on the rod 1022 equal and opposite theforce applied to the piston 1024 by the pressurized gas in the firstcylinder chamber 1026.

Simultaneously with pressurized gas entering the first cylinder chamber1026 via the first valve assembly 1042 (arrow A8 in FIG. 18A), thepressurized gas within the second cylinder chamber 1028 is exhaustedthrough the second flow control valve 1232 and the second inlet/outletport 1266 (FIG. 14; i.e., functioning as an outlet port) on route to theexhaust 1032 (arrow A9 in FIG. 18B). Because the second valve assembly1224 does not include a check valve, the pressurized gas in the secondcylinder chamber 1028 is exhausted through the flow control valve 1232at a volumetric or mass flow rate that is dependent upon the degree towhich the flow control valve 1232 is opened. In other words, the greaterthe spacing between the step 1300 on the needle 1246 and the seat 1302defined on the insert 1244, the higher the flow rate that gas can beexhausted from the second chamber portion 1028, and the smaller thespacing between the step 1300 on the needle 1246 and the seat 1302defined on the insert 1244, the lower the flow rate that gas can beexhausted from the second chamber portion 1028. Accordingly, during theextension operation shown in FIGS. 18, 18A, and 18B, the second flowcontrol valve 1232 meters the return of pressurized gas from the secondcylinder chamber 1028 to the exhaust 1032. In practical applications,the degree to which the flow control valve 1232 is opened is preset andremains unchanged during operation.

When the extensible rod 1022 has translated the desired amount, orattained an equilibrium of forces acting on it, the three position valve1038 is returned to the first position, coinciding with the second modeof operation. In the second mode, the three position valve 1038 connectsboth of the first and second inlet/outlet ports 1186, 1266 (FIG. 12) tothe exhaust. The valve system 1010 and cylinder 1012 may be operated inthe second mode, for example, when it is desired to maintain a clampingforce on an object, with the rod 1022 extended, but fluidly disconnectthe first cylinder chamber 1026 from the source 1030 of pressurized gas.

As shown in FIGS. 19, 19A, and 19B, a retraction operation is performedin the third mode. In the third mode, the three position valve 1038 isshifted to the third position and connects the pressurized gas source1030 to the second valve assembly 1224 and connects the first valveassembly 1042 to the exhaust 1032. Specifically, the second inlet/outletport 1266 functions as an inlet to direct the pressurized gas toward thesecond flow control valve 1232. Upon entering the second inlet/outletport 1266, the pressurized gas passes to the second cavity 1240 and actson a first side 1304 of the one-way seal 1248 to inwardly deflect therim 1306 of the one-way seal 1248 (arrow A10 in FIG. 19B), permittingthe pressurized gas to bypass the second flow control valve 1232 andenter the first cavity 1236 of the valve body 1226. Once in the firstcavity 1236, the pressurized gas builds pressure within the secondcylinder inlet/outlet port 1018 and the second cylinder chamber 1028.The increase in pressure in the second cylinder chamber 1028 (i.e.,applied by the pressurized gas) applies a force to the piston 1024,thereby retracting the rod 1022. The rod 1022 retracts at a speed thatis dependent upon the degree to which the first flow control valve 1136is opened until the piston 1024 bottoms out or stops in response to theapplication of a reaction force on the rod 1022 equal and opposite theforce applied to the piston by the pressurized gas in the secondcylinder chamber 1028.

Simultaneously, the pressurized gas continues along a second path (arrowA11), which extends around the flow control valve 1232 and through thesecond cavity 1240 of the valve body 1226, to the second pilot port 1234and the second fitting 1282 (which supports a second end of the hose1206). The pressurized gas enters the second end of the hose 1206,traverses the hose 1206, and exits the first end of the hose 1206 todisplace the plunger 1074 and unseat the seal member 1058 in a mannersimilar to that described above with respect to the third mode of valvesystem 10. Pressurized gas within the first cylinder chamber 1026 isvented to the exhaust 1032, past the unseated seal member 1058 andthrough the first flow control valve 1136 (arrow A12 in FIG. 19A) as thesecond cylinder chamber 1028 is simultaneously flooded with pressurizedgas (arrow A10).

As shown in FIGS. 19, 19A, and 19B, when the extensible rod 1022 hastranslated the desired amount, or attained an equilibrium of forcesacting on it, the three position valve 1038 is returned to the firstposition. As the pressure within the second valve assembly 1224 and thesecond chamber portion 1028 is exhausted, pressure within the hose 1206decreases, allowing the plunger 1074 and the seal member 1058 to returnto their biased positions. Therefore, the second cylinder chamber 1028vents to the exhaust 1032 until the first and second chamber portions1026, 1028 achieve equilibrium.

Further, as shown in FIGS. 20, 20A, and 20B, the plunger 1074 may bemanually actuated via operator input or contact with the button 1126.When an operator depresses the button 1126 (e.g., with a screwdriver,with a finger, etc.), the button 1126 and plunger 1074 move toward theseal member 1058 in unison to unseat the seal member 1058 as describedabove, venting pressurized gas from the first cylinder chamber 1026through the flow control valve 1136 along arrow A12, to the exhaust 1032when the valve 1038 is in the first position.

Various features of the invention are set forth in the following claims.

What is claimed is:
 1. A valve system for use with a cylinder having anextensible rod, the valve system comprising: a first valve assemblyincluding a first inlet/outlet port, a check valve biased toward aclosed state, the check valve having a check valve body at leastpartially receivable within a first port of the cylinder, a flow controlvalve positioned in series between the first inlet/outlet port and thecheck valve, and a first pilot port selectively communicable with asource of pressurized gas for opening the check valve; and a secondvalve assembly including a second inlet/outlet port, a second pilot portthrough which the pressurized gas must flow before being introduced tothe first pilot port, a valve body at least partially receivable withina second port of the cylinder, a first banjo fitting in which the secondpilot port is defined, and a second banjo fitting in which a second flowcontrol valve is received, wherein the first and second banjo fittingsare stackable upon the valve body.
 2. The valve system of claim 1,further comprising a hose interconnecting the first and second pilotports.
 3. The valve system of claim 2, further comprising: a firstquick-lock fitting securing a first end of the hose to the first pilotport; and a second quick-lock fitting securing a second end of the hoseto the second pilot port.
 4. The valve system of claim 1, wherein theflow control valve in the first valve assembly is a first flow controlvalve, and wherein the second valve assembly further comprises a secondflow control valve positioned in series between the second inlet/outletport and the valve body.
 5. The valve system of claim 1, wherein thecheck valve further comprises a seal member movable between a firstposition, in which a flow of pressurized gas between the firstinlet/outlet port and the first cylinder port is inhibited, and a secondposition, in which a flow of pressurized gas between the firstinlet/outlet port and the first cylinder port is permitted, and aplunger for moving the seal member from the first position to the secondposition in response to an application of force on the plunger.
 6. Thevalve system of claim 5, wherein the check valve further comprises abutton coupled to the plunger that is accessible by an operator outsidethe check valve body, and wherein the button and the plunger are movabletogether in response to the operator depressing the button to displacethe seal member from the first position to the second position.
 7. Thevalve system of claim 5, wherein the plunger defines a longitudinal axisalong which the plunger is movable, and wherein the plunger includes asurface oriented transverse to the longitudinal axis against whichpressurized gas from the first pilot port acts to move the plunger anddisplace the seal member from the first position to the second position.8. The valve system of claim 7, wherein the first valve assembly furthercomprises a spring biasing the plunger away from the seal member.
 9. Thevalve system of claim 5, wherein the first valve assembly furthercomprises a spring biasing the seal member toward the first position.10. The valve system of claim 5, wherein the seal member is a ball. 11.The valve system of claim 1, wherein the first valve assembly furthercomprises a one-way seal in parallel with the flow control valve, andwherein the one-way seal is also positioned in series between theinlet/outlet port and the check valve.
 12. The valve system of claim 11,wherein the one-way seal permits bypass of the flow control valve bypressurized gas acting on a first side of the one-way seal, permittingthe pressurized gas to flow directly from the inlet/outlet port to thecheck valve.
 13. The valve system of claim 12, wherein the one-way sealprevents bypass of the flow control valve by pressurized gas acting on asecond side of the one-way seal, causing the pressurized gas to flowthrough the flow control valve before entering the first inlet/outletport.
 14. The valve system of claim 13, wherein the one-way sealsurrounds at least a portion of the flow control valve, and whereinpressurized gas acting on the first side of the one-way seal can flowaround the one-way seal to bypass the flow control valve.
 15. The valvesystem of claim 1, wherein the check valve body includes a threaded endconnectable to the first cylinder port, and wherein the threaded end hasa thread form compatible with a plurality of different threadconfigurations.
 16. The valve system of claim 1, wherein the secondpilot port and the second inlet/outlet port are integrally formed as asingle piece.
 17. The valve system of claim 4, further comprising achamber fluidly communicating the second inlet/outlet port and thesecond pilot port, the chamber surrounding the second flow controlvalve.
 18. The valve system of claim 1, wherein the first valve assemblyfurther comprises a third banjo fitting in which the first pilot port isdefined, and a fourth banjo fitting in which the flow control valve isreceived, and wherein the third and fourth banjo fittings are stackableupon the check valve body.
 19. The valve system of claim 1, wherein thevalve body is positioned in series between the second inlet/outlet portand the second pilot port.